Controlling of forestry fires by means of aerial bombing with water, or by water with fire retardant, has proved to be particularly successful. It enables fire control personnel to start dealing with a new fire within a matter of a few hours from when it is first detected, even though the fire may be located in remote bush country which is inaccessible by land.
In the past, water bombers have usually been relatively small sea planes or large amphibious aircraft. Such amphibious aircraft usually have a central fuselage which is equipped with a profile or hull having a lower shape which is adapted to land on the water, and is equipped with wing tip floats to balance the aircraft when on the water. Small sea planes in the past have been equipped with external water bombing tanks fitted to the floats of the aircraft, or with integral tanks located within the floats.
In most cases, either water is taken into the plane, in an integral compartment in the main hull of the plane, or in external tanks by skimming or taxiing across the surface of a lake. The water is then released by flying over strategic points of the fire, and opening doors in the main hull, or in each aircraft pontoon, or in tanks. Older sea planes equipped with external tanks released water by mechanically rolling the tanks over and dumping water out of the tanks.
Amphibious water bombers are relatively large and represent a substantial investment, and are costly to maintain and costly to operate.
Sea planes must normally be located at central water base facilities, where such planes can be maintained and such facility must also have access to water for take-off and landing of the aircraft.
It has been found to be desirable to provide a more versatile form of water bomber, which is adapted as an amphibian, so that it has wheels to land and take off from a runway, and floats to land and take off on the water, and which is somewhat smaller and less expensive to buy and operate. In addition, such aircraft can be dispersed somewhat more widely in the locality of smaller lakes or landing strips where fires may be expected, so that the flying time from the take-off point to the fire may be greatly reduced. This will also give the aircraft greater endurance time over the fire before it must return to its base to refuel.